Mission boxes, how do they work?

[berryhog]

You know the boxes that appear on the left side of the screen telling you what you have to do. I got several boxes until level 15 and they stopped coming on. Im on level 30 now. My friend claimed she never has any mission boxes while another friend keeps having them, what's the deal with those boxes? Are they random? How do you keep getting them?

[ahshan]

They're just quests for you to do and to add more purpose to the game.
There's a whole line of them. Don't know if they unlock at later levels, but you eventually finish all the quests and no more come.
Some people are unable to get the quests due to some sort of glitch that probably will never be fixed.
Tip: There is no big prize at the end of the line of quests so it may not be worth your time to do all of them.